We had a Serrano and a near-identical Oliver(with a busted pedal brake...had to e-a-s-e the tension on to keep the string from snapping)...took about twice as long to string on the Oliver. This was in the mid-'70s until we got our first Ektelon. Got spoiled for a few years until I moved to Atlanta and worked at a shop that had FIVE Serranos(before switching completely to Prince P-100/200). Fortunately, the club where I strung had Ektelon and I bought one for myself. Then Babolat came along with the Star, Star 2 and Star 3...great machines.
True Tension sold quite a few machines in North Carolina in the '80s, but I don't recall seeing them in Atlanta. Maybe it was the same sales rep that sold the gahd-awful turf and sand courts all over the Carolinas.